|Score|2007|2008|2009|2010|2011|2012|2013|
|---|---|---|---|---|---|---|---|
|5|15.3%|18.4%|18.0%|17.1%|17.0%|16.4%|18.9%|
|4|18.0%|17.5%|17.9%|18.5%|18.4%|19.3%|21.5%|
|3|23.0%|20.0%|20.2%|19.3%|19.5%|20.1%|18.8%|
|2|18.5%|14.3%|14.2%|12.7%|14.6%|15.0%|14.9%|
|1|25.3%|29.9%|29.8%|32.3%|30.4%|29.2%|26.0%|
|Mean|2.79|2.80|2.80|2.76|2.77|2.79|2.92|
|Number of Students|97,136|100,586|104,789|115,077|122,651|132,425|140,006|

Question: what is the difference between 2008 and 2009 score?
Answer: 0